The present invention relates to a modular prosthetic implant system. In particular, this invention relates to such a system which includes modular stem extensions.
While this invention is particularly suitable for modular tibial prosthesis components having modular stem extensions, the features of this invention could be adapted, as appropriate, to other prosthetic components which utilize modular stem components.
It is well known in the art to utilize modular stem extensions. The following patents disclose the use of modular stem extensions which are straight and aligned with the attachment mechanism: U.S. Pat. Nos. 4,936,853; 4,950,298; and 4,959,071, while U.S. Pat. No. 4,822,366 discloses both a straight modular stem and a modular stem having a bowed or curved end portion.
In addition, U.S. Pat. No. 4,834,081 discloses a modular stem extension which is angled realtive to the prosthesis; while the following patents each disclose modular stems in which the modular angled stem can be attached to the prosthesis base in a plurality of positions to selectively vary the orientation of the angled stem relative to the prosthesis base: U.S. Pat. Nos. 4,822,365; 4,985,037; 5,133,760; 5,152,796.
In addition, U.S. Pat. No. 4,950,297 is noted of related interest. It discloses a control peg 21 which is fitted between the tibial and meniscal components. The control peg includes superior and inferior axial portions which are connected by a collar and are laterally offset from each other. The control peg controls subluxation and/or rotation of the meniscal component with respect to the tibial component. This patent is cited to point out the offset relationship of the control peg. However, it is noted that the control peg of this patent is not a stem extension, and it is utilized in a different manner and for a different purpose than the offset stem extension of the present invention.